基于ANS平行激活的三种数值加工机制

数值加工被证实依赖多种机制完成，“三数值加工系统学说”提出，加工不同密度的刺激，分别激活感数（subitizing）、数量和密度机制；然而三者的性质和关系尚待推敲。项目将修正、支持及拓展原学说。研究一验证：只要刺激的分布规律性足够高，密度机制的准确性超过数量机制，加工就会从数量机制切换到密度机制，修正“数量机制失效导致加工切换”的观点。研究二从多方面证实三个机制的差异，揭示“中等规律刺激引发的加工”有ANS的特点，直接分析数量；“高规律刺激引发的加工”对密度敏感，通过分析刺激的最小间距来推测数量。研究三将展示：在适当的注意负荷下，感知数量的韦伯定律可以普遍地被揭示；数量机制平行于感数和密度机制激活，当后两种机制被干扰时，加工依赖数量机制完成，展现出ANS加工的特征。研究四提出“基于ANS平行激活的三数值加工系统”模型，阐明数量机制普遍地激活、加工则在三种机制间灵活切换的模式。

According to recent frameworks of Three Number System, numerosity perception may be subserved by multiple mechanisms, subitizing, numerosity, and density, preferentially engaged under different circumstances, and particularly as a function of the number or density of items to be estimated. However, the relationship among these three systems is not well illuminated. In the current project, The Three Number System Theory will be modified, supported and extended. A link will be constructed between this theory and the Approximate Number System (ANS) Theory. Firstly, factors relevant to numerosity-density processing switching will be demonstrated. Distribution regularity is proposed to be critical in triggering the switching. Switching will happen as soon as the sensitivity of density mechanism precedes that of numerosity mechanism. Secondly, it will be revealed that numeral processing of stimuli with moderate regularity shares properties with ANS, and numerosity is sensed directly in this processing. On the other hand, observers are more sensitive to density feature of high-regularly-distributed stimuli, and the nearest distance between dots would be analyzed to infer numerosity. Evidences will be converged to show that numerosity and density mechanisms are distinct. Thirdly, numerosity mechanism will be revealed in a wider range. With proper attention loading, Weber’s law for sensing numerosity will be demonstrated even within the subitizing and density range. When the later two mechanisms are inhibited, numerosity takes the job, and processing therefore shows features similar to those of ANS. Fourthly, a cognitive model, Three Number System based on parallel activation of ANS, is proposed. According to the model, numerosity or ANS mechanism is activated in parallel within the whole number range, while cognitive activity switches among subitizing, numerosity, and density mechanisms. Better processing results can be achieved by switching processing mechanisms according to stimuli features.